typespec-java, eng, Move away from PowerShell script in build

[weidongxu-microsoft]

PowerShell shows strange behavior in multiple cases.

Previously it break Azure pipeline when write to stderr.

Here it write terminal cursor/control during file remove/copy and breaks turbo #5004

We may want to migrate these scripts (at least those used during CI) to TypeScript script.

• On node 22+ there is no need to compile to JS
• Use exca for external tool calls